Fluid sampling extends over a wide range of fields, including atomic absorption spectroscopy and liquid chromatography. In these latter fields, unknown elements in solution are supplied in sample test tubes which are sequentially analyzed by the parent instrument.
Ideally, many vials of sample are pre-arranged in trays or racks for positioning on a sampler platform which cooperates with the instrument in sequentially analyzing the solution in each vial. Typically, the sample vials are disposed in a circular tray or in linear racks.
Heretofore, the circular tray arrangements provided for a singular circular row disposed near the perimeter of the tray. Typically samplers introduce the sampling probe into the vials in either an arcuate type motion or with an up-down motion interspersed with a step positioning of the tray so as to sample successive vials. A typical example of a circular tray sampler with a single row of test vials and an up-down motion is described in U.S. Pat. No. 3,546,946.
Generally, the access time for the probe to leave one vial and thereafter access a second vial should not be a limiting factor in the operation of the overall system. In other words, it should be the actual analyzing instrument itself which controls the time for analysis and not the time required to access each successive vial. For example, in the field of atomic absorption spectroscopy, the analysis time for typically sized samples would be approximately 5 seconds. Therefore, the time between sample access should be less than this so that upon completion of a first analysis, the sampling equipment is ready to provide the subsequent specimen.
Further, the so-called through-put of the system (the number of sample vials processed per unit of time) can be enhanced and the total analysis time reduced if the vial density for each tray is increased. Further, with respect to the vials employed, the cost of a system can be reduced if the sampler employs standard test tubes, for example, the 15 milliliter size readily available from equipment supplies.
Of course, in increasing the vial handling capacity of the tray, the size should not be so large as to make its handling cumbersome. Also, it is desirable that the tray with the vials in place be removed as a unit from the sampler platform and a substituted tray disposed thereon to again speed up the analysis of the total number of sample vials.
Of course, the simpler the mechanics to implement such a system, the more reliable the overall system.
It is therefore a primary object of this invention to provide a fluid sampler which improves the vial through-put capability of a sample analysis system.
It is still another object of this invention to provide a relatively simple mechanical device for improving the fluid sampling through-put.
It is yet another object of this invention to provide a fluid sampler employing a circular tray, wherein the vial density per tray is increased without significantly increasing the overall dimensions of the circular tray.